Ametek 7270 Instruction Manual page 152

Chapter 6, COMPUTER OPERATION
IE2 [n]
REFN [n]
REFP[.] [n]
AQN
FRQ[.]
FRQ1[.]
FRQ2[.]
6-14
Reference channel 2 source control, Dual Reference
In Dual Reference mode, the value of n sets the reference channel 2 source according
to the following table:
n Selection
0 INT (internal)
1 EXT (external rear panel TTLREF IN input)
2 EXT (external front panel analog REF input)
This command is only valid in Dual Reference mode
Reference harmonic mode control
The value of n sets the reference channel to one of the NF modes, or restores it to the
default 1F mode. The value of n is in the range 1 to 127.
Reference phase control
In fixed point mode n sets the phase in millidegrees in the range ±360000.
In floating point mode n sets the phase in degrees.
Auto-Phase (auto quadrature null)
The instrument adjusts the reference phase to maximize the X channel output and
minimize the Y channel output signals.
Reference frequency meter
If the lock-in amplifier is in the external reference source modes, the FRQ command
causes the lock-in amplifier to respond with 0 if the reference channel is unlocked, or
with the reference input frequency if it is locked.
If the lock-in amplifier is in the internal reference source mode, it responds with the
frequency of the internal oscillator.
In dual reference mode it reports the frequency of the reference 1 channel.
In fixed point mode the frequency is in mHz, and in floating point mode the
frequency is in Hz.
Reference frequency meter, reference 1 channel
In dual reference modes, the FRQ1 command causes the lock-in amplifier to respond
with 0 if the reference 1 channel is unlocked, or with the reference input frequency if
it is locked.
In fixed point mode the frequency is in mHz, and in floating point mode the
frequency is in Hz.
Reference frequency meter, reference 2 channel
In dual reference modes, the FRQ2 command causes the lock-in amplifier to respond
with 0 if the reference 2 channel is unlocked, or with the reference input frequency if
it is locked.
In fixed point mode the frequency is in mHz, and in floating point mode the
frequency is in Hz.